Enlarge / A dive into a Metro Exodus sewer leads to this creature, which 4A Games calls a "humanimal." This image was provided by the publisher, however, and looks touched up compared to the two hours of gameplay we tested before E3. (credit: 4A Games)

SANTA MONICA, Calif.—The Ukrainian game developers at 4A Games don't hesitate to list Half-Life 2 as a defining inspiration for Metro, their long-running first-person shooter series. A 4A representative at a pre-E3 event in May cited Valve's linear storytelling and knack for cinematic presentation as defining tentpoles for the games Metro 2033 and Metro: Last Light, which the studio now calls "two halves of the same game."

So what, then, has driven inspiration and development on next year's sequel Metro Exodus? 4A isn't specific. Instead, it vaguely refers to modern gaming as "the era of the best single-player games in years." That's its competition, the studio says.

But after two hours playing through the massive, harrowing, open-world terror of Metro Exodus, it's hard to escape the feeling that 4A had a specific goal in making a new, epic game with the word "Metro" on the title: not to beat an existing game, but to make the open-world version of Half-Life that Valve never got around to slapping the number "3" onto.